It's the second mishap Williams has encountered since the Celtics selected him 27th overall in the 2018 NBA draft. He missed his media conference call the morning following the draft after oversleeping.

According to The Athletic'sJay King, Celtics assistant coach JayLarranagasaid the team will deal with Williams' absence internally.

Williams' talent and potential weren't in question heading into the NBA draft. He averaged 11.1 points, 8.7 rebounds and 2.5 blocks in two years with the Texas A&M Aggies.

However, ESPN's AdrianWojnarowskiwas among those highlighting the biggest criticism around Williams:

Adrian Wojnarowski @wojespn

Williams is a lottery-level talent, a player with immense talent. If he can show a commitment to playing hard, this could be a steal of the first-round. ESPN's @Mike_Schmitz compares him to another 27th overall pick: Clint Capela. https://t.co/9zFvD7MWiM

During Williams' introductory press conference with the Celtics, head coach Brad Stevens and general manager DannyAingeattempted to downplay any early issues with his commitment:

Brian Robb @BrianTRobb

Brad Stevens says Robert Williams has been in the gym every day thus far and got a workout in already this morning at 630.

Brian Robb @BrianTRobb

Danny Ainge on criticism that Robert Williams can have a low motor at times: "It's hard to have a low motor and be defensive player of the year twice in a good conference."

Neither of Williams' infractions is significant on its own, but together they'll likely be a source of frustration for the Celtics. It's the exact opposite kind of impression the rookie will have wanted to make on his new team.

Williams will make his Celtics debut in the NBALasVegas Summer League. Boston faces off with the Philadelphia 76ers on Friday.